How To Use The Filter Block
The filter block evaluates an expression as either True or False, then sorts the data into the Pass and Reject nodes. Data at the Pass node are those rows which evaluates to True, while data at the Reject node are those that evaluate to False.
1. The first step is to drag and drop the Filter block on to the Canvas.
2. Click on the output node of any block, then drag and release on the input node of the Filter block.
3. Select the Filter by clicking in the center of the block. You will see the configuration area at the bottom of the screen; click on the field to edit the filter expression.
4. Your formula will go into the Calculation field. The result of the expression must be a boolean (a 'True' or 'False' value). The filter then tests for this value and allows you to use the results of both values in your workflow.
In the "Function Reference" column, you will find all available formulas. You can search for a function or click on the different types to see the formulas in that category. When you click on a formula, its structure will appear above the search bar. If you double-click on it, the function will be added to the Expression Window.
You will see all available columns from the table you are filtering to the right of the functions. You can also use the search field to find a given column,. When you click on a column it will be added to the Expression Window.
In the Expression Window, enclose string values in double-quotes. For example,
use: [Original.Brand] = "Acme Premier"
not: [Original.Brand] = Acme Premier
5. When you have entered an expression, click "Validate" to check if the expression can be run. If it is valid, you will see the Generated SQL, otherwise, you will see an error message.
To test the value of a Boolean column, simply enter the column name in the calculation field, then click OK. Results that are True will be available on the top right node of the Filter block.
6. Select "Data Preview" to see a preview of the processed data.
7. The first output node is for the data that matches the filter's expression, returning a TRUE value. The second output on the bottom is for the data that doesn't match the filter expression (returns FALSE).